What to do at Dry Tortugas
Tour historic Fort Jefferson
After the War of 1812, the US built a series of coastal forts to protect its eastern border, stretching from Maine to Florida. The one erected on Dry Tortugas' Garden Key -- Ft. Jefferson -- was an epic project containing 16 million red bricks, and the most advanced military building project of its time. The six-sided fort doesn’t contain a single construction joint, but still sports arches and entryways, and is the largest masonry structure in the Western Hemisphere. And on a hot day it can expand nearly 2ft in width without any residual damage.
At its height, the fort housed 1,729 people and was more densely populated than Manhattan. But beyond troops, the fort also served as an island prison, like a Florida version of Alcatraz. It mostly housed army deserters, but its most notable inmate was Dr. Samuel Mudd, the man who assisted and housed John Wilkes Booth for two days after he assassinated Abraham Lincoln -- along with the quotable Samuel Arnold.
You can take a ranger-led tour of the fort most days as part of your $10 park admission. But the tours aren't scheduled regularly so if you take your own boat in you'll have to see when -- and if -- they're running. If you take the ferry out, a scheduled tour is included in the price. Self-guided tours are, of course, always available.